Methods using peracids for controlling corn ethanol fermentation process infection and yield loss

Abstract

A process for the use of peracid compositions to eliminate and/or control the growth of undesirable bacteria, including contaminating bacteria, in the fermentation production of alcohol is disclosed. Beneficially, the peracid compositions and methods of use of the same do not interfere or inhibit the growth or replication of yeast and have low or no adverse environmental impact.

What is claimed is: 
     
       1. A method for reducing and/or eliminating microbial populations of yield loss organisms in a biofuel fermentation system comprising:
 applying a peracid composition to sanitize a biofuel fermentation system, wherein the peracid composition comprises a medium chain peracid and peroxyformic acid and wherein the fermentation system comprises one or more fermentation vessels, pipes and/or components; 
 providing or obtaining a mash source in said fermentation system; 
 fermenting the mash source in the presence of at least a residual portion of the peracid composition with yeast to produce ethanol and a solids content; and 
 reducing and/or eliminating the microbial populations of yield loss organisms in said fermentation system, wherein the yield loss organisms are lactic acid bacteria and/or acetic acid bacteria, and wherein said peracid composition does not carry through the fermentation process in amount or concentrations in the solids content that cause animal feeding concerns. 
 
     
     
       2. The method of  claim 1 , wherein the lactic acid bacteria and/or acetic acid bacteria are one or more of  Acetobacter, Leuconostor , and  Weissella.    
     
     
       3. The method of  claim 1 , wherein the peracid composition comprises peroxyoctanoic acid, octanoic acid, hydrogen peroxide and water and does not include acetic acid and/or peracetic acid. 
     
     
       4. The method of  claim 1 , wherein the peracid composition comprises from about 0.5 wt-% to about 5 wt-% peroxyoctanoic acid, from about 1 wt-% to about 10 wt-% octanoic acid, from about 5 wt-% to about 97 wt-% water, from about 0 wt-% to about 20 wt-% anionic surfactant, from about 0 wt-% to about 10 wt-% oxidizing agent; about 0 wt-% to about 35 wt-% inorganic acid, and from about 0 wt-% to about 5 wt-% sequestrant. 
     
     
       5. The method of  claim 1 , wherein said peracid composition controls growth of bacteria in the mash without reducing yeast population; and the fermented mash is distilled to separate at least a portion of the ethanol from said solids content, wherein the solids content is fed to livestock. 
     
     
       6. The method of  claim 1 , wherein the peracid composition and/or reduction of microbial population does not interfere with yeast fermentation. 
     
     
       7. A method for reducing yield loss in ethanol biofuel fermentation processes comprising:
 applying a peracid composition to sanitize a biofuel fermentation system, wherein the peracid composition comprises a medium chain peracid and peroxyformic acid; 
 fermenting a mash in the presence of at least a residual portion of said peracid composition and yeast in a vessel of said fermentation system to produce ethanol and a solids content; 
 reducing a microbial population of lactic acid bacteria and/or acetic acid bacteria to reduce yield loss in the ethanol fermentation process; and 
 distilling the fermented mash to separate at least a portion of the ethanol from said solids content, 
 wherein the antimicrobial efficacy of said peracid composition does not interfere with yeast fermentation, and wherein said peracid composition does not carry through the fermentation process in amounts or concentrations in the solids content that cause animal feeding concerns. 
 
     
     
       8. The method of  claim 7 , wherein said peracid composition is applied to said fermentation system for providing sanitizing of said system without requiring a rinse step of said fermentation system, and wherein said portion of said peracid composition is a residual amount remaining in said vessel after sanitizing. 
     
     
       9. The method of  claim 7 , wherein the peracid composition comprises peroxyoctanoic acid, octanoic acid, hydrogen peroxide and water. 
     
     
       10. The method of  claim 7 , wherein the bacteria are  Acetobacter  species. 
     
     
       11. A method for replacing antibiotics in biofuel fermentation processes comprising:
 replacing an antibiotic used in a biofuel fermentation process to reduce and/or eliminate  Lactobacillus  and/or  Acetobacter  species with a peracid composition for application to a fermentation system; and 
 introducing the peracid composition to a mash source, wherein the peracid composition comprises from about 0.0005 wt-% to about 5 wt-% peroxyoctanoic acid and peroxyformic acid, from about 1 wt-% to about 10 wt-% octanoic acid and formic acid, from about 5 wt-% to about 97 wt-% water, from about 0 wt-% to about 20 wt-% anionic surfactant, from about 0 wt-% to about 10 wt-% oxidizing agent; about 0 wt-% to about 35 wt-% inorganic acid, and from about 0 wt-% to about 5 wt-% sequestrant, wherein the peracid composition does not interfere with yeast fermentation in a fermentation process, and wherein said peracid compositions does not carry through the fermentation process in amounts or concentrations that cause animal feeding concerns. 
 
     
     
       12. The method of  claim 11 , wherein the peracid composition comprises from about 0.5 wt-% to about 5 wt-% peroxyoctanoic acid and peroxyformic acid, from about 1 wt-% to about 10 wt-% octanoic acid and formic acid, from about 5 wt-% to about 97 wt-% water, from about 1 wt-% to about 20 wt-% anionic surfactant, from about 5 wt-% to about 10 wt-% oxidizing agent; about 15 wt-% to about 35 wt-% inorganic acid, and from about 1 wt-% to about 5 wt-% sequestrant. 
     
     
       13. The method of  claim 11 , wherein the peracid composition does not introduce to the biofuel fermentation system a source of acetic acid and/or peracetic acid. 
     
     
       14. The method of  claim 11 , further comprising fermenting the mash source in the presence of at least a portion of said peracid composition, and yeast in a vessel to produce ethanol and a solids content, wherein said peracid composition controls growth of bacteria in the mash without reducing yeast population; and distilling the fermented mash to separate at least a portion of the ethanol from said solids content. 
     
     
       15. The method of  claim 14 , further comprising obtaining a distillers dried grains product from said solid contents containing less than about 1000 ppm of the peracid composition. 
     
     
       16. The method of  claim 11 , wherein the peracid composition is introduced to the fermentation process within a clean-in-place application to clean the systems employed for the fermentation process. 
     
     
       17. The method of  claim 16 , wherein the peracid composition is introduced either upstream from a fermentation vessel or directly into the fermentation vessel. 
     
     
       18. The method of  claim 16 , wherein the peracid composition or a portion of the peracid composition is retained in the fermentation vessel after the clean-in-place application and used for reducing and/or eliminating the  Lactobacillus  and/or  Acetobacter  species during the fermentation process. 
     
     
       19. The method of  claim 11 , wherein the peracid composition is introduced to the fermentation process as a direct additive to the mash source. 
     
     
       20. The method of  claim 11 , wherein the peracid compositions have low or no adverse environmental impact. 
     
     
       21. The method of  claim 1 , wherein the amount of peracid compositions carrying through the fermentation process as residual peracid composition in the mash source is up to about 2,000 ppm. 
     
     
       22. The method of  claim 1 , wherein the peracid composition does not include a stabilizing agent. 
     
     
       23. The method of  claim 7 , wherein the amount of peracid compositions carrying through the fermentation process as residual peracid composition in the mash is up to about 2,000 ppm. 
     
     
       24. The method of  claim 7 , wherein the peracid composition does not include a stabilizing agent. 
     
     
       25. The method of  claim 11 , wherein the amount of peracid compositions carrying through the fermentation process as residual peracid composition in the mash source is up to about 2,000 ppm. 
     
     
       26. The method of  claim 11 , wherein the peracid composition does not include a stabilizing agent. 
     
     
       27. The method of  claim 1 , wherein the medium chain peracid is one of pentanoic acid, hexanoic acid, heptanoic acid, nonanoic acid, decanoic acid, undecanoic acid, and dodecanoic acid. 
     
     
       28. The method of  claim 7 , wherein the bacteria are one or more of  Lactobacillus, Pediococcus, Leuconostor , and  Weissella.    
     
     
       29. The method of  claim 11 , wherein the  Lactobacillus  and/or  Acetobacter  species is  Acetobacter  bacteria.